A typical meltable fuse-type electrical interrupter includes a conductor portion which melts upon reaching a threshold current, the melting being caused by the increase in temperature associated with the current increase and the accompanying I2R effect. Once melted, the molten conductor flows, as a result of gravity and/or surface tension, away from the related conductors and the fuse thereby opens the circuit. Devices of this sort are generally described in U.S. Pat. No. 4,368,452 to Kerr Jr. and U.S. Pat. No. 4,622,534 to Bowman.
Such fuse devices, however, are unsuitable for high current use. As currents increase, so too does the fusing temperature and, at very high currents, the fusing material will vapourize once the threshold current is reached, since the material cannot be removed from the vicinity quickly enough and electricity continues to flow through the molten conductor. Arcing results and, as arcing may continue to occur through the medium of the vapourized conductor, arc-extinguishing measures such as the provision for silica sand or a gas must be provided to permit the device to work as intended in high current circuits. The devices therefore often end up being complex, expensive, heavy and of decreased reliability.
Another drawback of the meltable fuse type interrupter is that gravity is relied upon to remove the melted conductor from the circuit to thereby open the circuit. In applications where fuse attitude or gravity may vary (e.g. airborne or space applications), these types of meltable fuses may also be unsuitable. Also, reliance on gravity slows response times. Accordingly, there is a need for improvements in interrupters, particularly for use in high current-carrying circuits and/or variable attitude applications, and it is an object of this invention to provide such a device.